Why aren't my threads running? - c++

Question

// windows_procon.cpp : Defines the entry point for the console application.
#include "stdafx.h"
#include <stdlib.h>
#include <iostream>
#include <time.h>
#include <windows.h>
#include <process.h>
using namespace std;
HANDLE mutex;
HANDLE emptySlots;
HANDLE filledSlots;
#define BUFFER_SIZE 10
void *producer(void *);
void *consumer(void *);
int produceItem(void);
void printBuffer(void);
int buffer[BUFFER_SIZE];
int head = 0;
int tail = 0;
int _tmain(int argc, _TCHAR* argv[])
{
DWORD prodThrdID, consThrdID;
mutex = CreateMutex(NULL,FALSE,NULL);
emptySlots = CreateSemaphore(NULL,BUFFER_SIZE,BUFFER_SIZE,NULL);
filledSlots = CreateSemaphore(NULL,0,0,NULL);
srand(time(NULL));
_beginthreadex(NULL, 0, (unsigned int(__stdcall *)(void*))producer,
0, 0, (unsigned int *)&prodThrdID);
_beginthreadex(NULL, 0, (unsigned int(__stdcall *)(void*))consumer,
0, 0, (unsigned int *)&consThrdID);
return 0;
}
void *producer(void *n)
{
int item;
for(int i = 0; i <BUFFER_SIZE+5; i++)
{
WaitForSingleObject(emptySlots,INFINITE);
WaitForSingleObject(mutex,INFINITE);
item = produceItem();
//printf("Producing");
cout << "Producing: " << item << endl;
//logfile << "Producing: "<< item << endl;
//fprintf(logfile, "Producing: %d \n", item);
buffer[head] = item;
head = (head + 1) % BUFFER_SIZE;
printBuffer();
ReleaseMutex(mutex);
ReleaseSemaphore(filledSlots,1, NULL);
}
return n;
}
void *consumer(void *n)
{
for(int i = 0; i <BUFFER_SIZE+5; i++)
{
WaitForSingleObject(filledSlots,INFINITE);
//Sleep(500);
WaitForSingleObject(mutex,INFINITE);
cout << "Consuming: " << buffer[tail] << endl;
buffer[tail] = 0;
tail = (tail + 1) % BUFFER_SIZE;
printBuffer();
ReleaseMutex(mutex);
ReleaseSemaphore(emptySlots,1, NULL);
}
return n;
}
int produceItem(void)
{
int x = (rand()%11 + 1);
return x;
}
void printBuffer(void)
{
for(int i = 0; i <BUFFER_SIZE; i++)
{
printf("%d ", buffer[i]);
}
printf("END \n");
}
My program here is supposed to be an algorithm for the producer-consumer problem. I think I have the algorithm correct my only problem is that I'm having trouble getting the threads to run properly. Can someone tell me what the issue is?

Answer 1

You need to wait for the threads you create with _beginthreadex to do their work, as it stands you program will exit immediately after creating them. I haven't looked any further at you logic.
Here is an example.
hThread = (HANDLE)_beginthreadex( NULL, 0, &SecondThreadFunc, NULL, 0, &threadID );
WaitForSingleObject( hThread, INFINITE );